An automated high-level topology generation procedure for continuous-time ΣΔ modulator

This paper presents an automated procedure for generation of high-level topologies for continuous-time ΣΔ modulator system. A functional topology of the system is generated from the given transfer function model of the modulator. Mathematical transformation technique is applied iteratively over the initial topology to generate a functional topology which is optimized for modulator sensitivity, hardware complexity and relative power consumption. This is then implemented using behavioral models of operational transconductance amplifiers and capacitors. The generated high-level topology is ensured to work with reasonable accuracy under non-ideal conditions. The entire procedure has been implemented in Matlab/Simulink environment. Numerical results have been provided to demonstrate the procedure.     

Hafnium or zirconium high-k fab cross-contamination issues

Hf and Zr contamination during immersion in process solutions is most likely to occur in neutral and caustic solutions. Both Hf and Zr contamination are introduced onto the wafer surface if they are present in an ammonium hydroxide peroxide mixture solution (which is caustic), but such contamination is removed using existing acid cleans. Large amounts of wafer-to-wafer cross contamination occurs in plasma etch tools. Particles can cause cross contamination in a thermal reactor during high-temperature anneals of high-k dielectric layers. Residual surface cross contamination does not diffuse into the wafers during thermal processing. If contamination remains on a wafer, gate oxide integrity degradation is only observed at high concentrations. Near surface minority carrier lifetime is also affected, but bulk lifetime is not.     

Proteomics analysis of carbon-starved Mycobacterium smegmatis: induction of Dps-like protein

Mycobacterium tuberculosis is a globally successful pathogen,infecting more than one third of total world's population. Thesebacteria have the remarkable ability to persist in the hostfor long periods of time unrecognized by the immune system andthen to re-emerge later in life causing the disease. The physiologyof such persistent or dormant bacilli is not very well characterized.Some evidence suggests that the dormant bacilli survive in anutrient-deprived state that is similar to the stationary phaseof the bacteria with respect to gene expression and physiology.Under this assumption we have studied the survival of Mycobacteriumsmegmatis in carbon starvation conditions as a model for mycobacterialpersistence. M.smegmatis, being a fast-growing strain, servesas a good model to study starvation responses. Using the two-dimensionalelectrophoresis-based proteomics approach, we identified a proteinwhich was found to be expressed preferentially under starvationconditions. This protein is homologous to a family of proteinscalled Dps (DNA binding Protein from Starved cells) that areknown to protect DNA under various kinds of environmental stressesand its existence has, so far, not been reported in mycobacteria.Upon expression and purification of this protein, we observedthat it has non-specific DNA-binding ability. Formation of acage-like dodecamer structure is a characteristic feature ofDps. Using comparative modelling we were able to show that Dpsfrom M.smegmatis could form a dodecamer structure similar tothe crystal structure of Dps from Escherichia coli.     

Cramer-Rao lower bounds for a damped sinusoidal process

The Cramer-Rao lower bounds (CRLBs) for the parameter estimators of a damped sinusoidal process are derived in this paper. Succinct matrix expressions for CRLB's of frequency, damping factor, amplitude, and initial phase are given for both scalar and vector processes. The relationships between the CRLBs of the characteristic parameters are established in the general multimode case. In particular, explicit, closed-form expressions for the single mode scalar/vector-damped/undamped cases are provided     

PEG based hyperbranched polymeric hollow nanospheres

The synthesis of a new PEG based hyperbranched copolymer of poly(ethylene glycol) methyl ether methacrylate-co-ethylene glycol dimethacrylate (PEGMEMA-co-EGDMA) was achieved via a one-step in situ deactivation enhanced atom transfer radical polymerization (DE-ATRP). Then, hollow PEG based nanospheres were fabricated from this polymer using a solvent evaporation method and post-stabilisation strategy. Furthermore, the analysis using a cellular metabolic activity assay proved that the copolymer did not affect cellular metabolism, indicating that this PEG based polymeric nanosphere has potential for use in drug delivery applications.     

Polyadenylation of stable RNA precursors in vivo

Polyadenylation at the 3' terminus has long been considered a specific feature of mRNA and a few other unstable RNA species. Here we show that stable RNAs in Escherichia coli can be polyadenylated as well. RNA molecules with poly(A) tails are the major products that accumulate for essentially all stable RNA precursors when RNA maturation is slowed because of the absence of processing exoribonucleases; poly(A) tails vary from one to seven residues in length. The polyadenylation process depends on the presence of poly(A) polymerase I. A stochastic competition between the exoribonucleases and poly(A) polymerase is proposed to explain the accumulation of polyadenylated RNAs. These data indicate that polyadenylation is not unique to mRNA, and its widespread occurrence suggests that it serves a more general function in RNA metabolism.     

Electrical conductivity,thermoelectric power and dielectric constant of a Gd2Ti2O7 single crystal

Electrical conductivity, thermoelectric power and dielectric constant of a Gd₂Ti₂O₇ single crystal have been studied in the temperature range 300–1000 K. Gd₂Ti₂O₇ is found to be an-type semiconductor with energy band gap 1.5 eV. It exhibits an extrinsic nature up to 675 K and an intrinsic nature above 675 K. The thermoelectric power increases with temperature in the region 300–675 K whereas it decreases with temperature in the region 675–1000 K. The dielectric constant increases slowly in the temperature range 300–675 K but this increase becomes fast in the temperature range 675–1000 K.     

In Vitro and Invivo Evaluation of Some Fast Release Dosage Forms of Hydrochlorothiazide

The utilization of ternary sugar solid dispersion and solvent deposition systems for increasing the dissolution rate of hydrochlorothiazide (hot) were investigated. The dispersion systems were prepared by the fusion method using various combinations of mannitol and sorbitol, and urea and polyethylene glycol 4000 (peg 4000) were used for comparison. An 1:2 mixture of sorbitol-mannitol was found to be an excellent carrier. The dissolution rate of this sample was closely comparable to that of hot-peg 4000 solid dispersions. Drug-urea eutectic mixtures were inferior to both the sugar and polymer dispersions. Solvent deposition systems of hot with microfine cellulose and potato starch gave higher dissolution rates at the initial sampling times. It is proposed that solid dispersion systems of this drug may prove to be valuable. Tablets fabricated from fast-release hot granules showed better in vivo results than a marketed tablet. A linear relationship was observed between in vitro-in vivo data of some of the products.